Reversible iodine electrodeposition based color-neutral wO3-i2 complementary electrochromic device and preparation method thereof

Abstract

The application provides a color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition and a preparation method thereof. The complementary electrochromic device comprises two conductive layers, an electrochromic layer and an electrolyte layer in the two conductive layers. The electrochromic layer is a cathode electrochromic material, and the electrolyte layer contains iodine ions. A voltage is applied through a conductive layer lead wire. When a positive voltage is applied, the device is in a colored state, and when a negative voltage is applied, the device is in a bleached state. Compared with a conventional complementary device, the non-metallic deposition complementary electrochromic device provided by the application only needs to prepare one electrochromic material, can increase the light transmittance, has deeper color superposition of iodine in the colored state, has a larger modulation rate, has a wider voltage window, can be used for preparing a large device, and has the advantages of simple preparation method, high transmittance and good cycle stability.

Description

Technical Field

[0001] This invention relates to the field of electrochromic device technology, and in particular to a color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition and its preparation method. Background Technology

[0002] Electrochromism is the phenomenon where the optical properties of a material undergo stable and reversible changes under different applied voltages, and it has broad application prospects in fields such as energy-saving windows, anti-glare rearview mirrors, and display panels. Electrochromic materials are mainly divided into inorganic electrochromic materials and organic electrochromic materials. Tungsten oxide (WO3) is one of the most promising inorganic electrochromic materials, highly regarded for its excellent electrochromic properties. However, the color change of a standalone WO3 device is limited to the transition from transparent to blue, lacking modulation across the entire visible spectrum. To address this limitation, researchers have explored various complementary electrochromic devices, including WO3-PANI, WO3-NiO, and WO3-PB devices. These combinations aim to achieve a wider optical modulation range across wavelengths and improve overall electrochromic performance. Although progress has been made in optical modulation rates, achieving color-neutral electrochromic tone modulation remains extremely challenging. Besides exploring novel electrochromic materials, integrating traditional electrochromic techniques with reversible metal deposition / dissolution techniques into the same device also offers possibilities for achieving excellent color-neutral electrochromism. For example, researchers have developed a multi-step electrochemical reaction strategy to improve overall electrochromic performance. This strategy involves the deposition of Nb... 18 W 16 O 93 Multiple processes, including Zn, are implemented on electrochromic thin films. 2+ Adsorption / desorption, insertion / extraction, and reversible electrodeposition (ACS Energy Letters 2023, 2300-2307). However, since all these electrochemical reactions occur on the same electrode, and the counter electrode can only be placed around the device with a relatively long ion transport path, there is a significant challenge in realizing large-area uniform devices. Summary of the Invention

[0003] Therefore, the purpose of this invention is to propose a color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition and its preparation method, and to propose an application of non-metallic iodine deposition in complementary electrochromism.

[0004] The technical solution of this invention is implemented as follows:

[0005] A color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition is described. The complementary electrochromic device includes two conductive layers, an electrochromic layer and an electrolyte layer within the two conductive layers. The electrochromic layer is a cathode electrochromic material, and the electrolyte layer contains iodine ions. A voltage is applied through a wire connected to the conductive layer. When a positive voltage is applied, the device is in a colored state, and when a negative voltage is applied, it is in a decolored state.

[0006] A further option is that the coloring state is achieved when a positive voltage of 1.0 to 2.0V is applied, preferably with a coloring voltage of 1.5 to 1.8V.

[0007] A further option is that the color fades when a negative voltage of -2.0 to -1.0V is applied, preferably a color fading voltage of -1.4 to -1.6V.

[0008] A further embodiment is that the conductive layer is a transparent conductive layer, including a rigid conductive electrode and a flexible conductive electrode. The rigid conductive electrode includes, but is not limited to, at least one of FTO glass, ITO glass, AZO glass or conductive graphene glass, and the flexible conductive electrode includes, but is not limited to, at least one of PET / ITO, PET / graphene electrode or PET / conductive polymer.

[0009] A further embodiment is that the rigid conductive electrode further includes FTO glass, ITO glass, and AZO glass modified with conductive polymers or nanoparticles. The conductive polymers include, but are not limited to, at least one of polyaniline, polythiophene, or polypyrrole, and the nanoparticles include, but are not limited to, at least one of Pt nanoparticles, Au nanoparticles, and ITO nanoparticles.

[0010] A further option is that the cathode electrochromic material is tungsten trioxide.

[0011] A further embodiment is that the cathode electrochromic material is deposited on a conductive layer by magnetron sputtering, electrochemical deposition, hydrothermal method or spin coating, preferably magnetron sputtering.

[0012] A further embodiment is that the electrolyte layer is a blend of zinc iodide and zinc salt electrolyte solution, wherein the zinc salt electrolyte solution includes an organic solution of zinc salt or an aqueous solution of zinc salt, preferably, the organic solution of zinc salt is a salt-in-water electrolyte solution of zinc salt.

[0013] A further embodiment is that the zinc salt electrolyte solution is a zinc chloride electrolyte solution in water, and the preparation method of the blend of zinc iodide and zinc salt electrolyte solution includes: adding zinc chloride to heated water, adding zinc iodide when the solution is close to saturation until the mixed solution is saturated, to obtain the blend of zinc iodide and zinc salt electrolyte solution.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] Compared with traditional complementary devices, the non-metallic deposition complementary electrochromic device of iodine provided by this invention only requires the preparation of one electrochromic material to increase light transmittance, and the color of iodine is more deeply superimposed during coloring, achieving color-neutral electrochromic performance. The device has a larger modulation rate and good cycle stability.

[0016] This invention uses a salt-in-water electrolyte to prepare electrochromic devices, which have a wide voltage window. At the same time, the application of non-metal deposition on complementary electrochromic devices can be used to prepare large devices. The preparation method is simple and has high transmittance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the non-metallic deposition complementary electrochromic device of iodine of the present invention, wherein 1 and 4 are a layer of transparent conductive glass, 2 is a cathode electrochromic material, and 3 is an electrolyte layer.

[0018] Figure 2 This is a transmission image of the WO3-I2 complementary electrochromic device.

[0019] Figure 3 The diagram shows the cyclic performance of the WO3-I2 complementary electrochromic device.

[0020] Figure 4 This is a schematic diagram of the structure of a WO3-PANI complementary device, where 1 and 5 are a layer of FTO transparent conductive glass, 2 is WO3, 3 is the electrolyte, and 4 is PANI.

[0021] Figure 5 This is a transmission image of a WO3-PANI complementary electrochromic device. Detailed Implementation

[0022] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0024] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0025] Example 1 - Iodine Nonmetal Deposition Complementary Electrochromic Device

[0026] like Figure 1As shown, in the iodine nonmetal deposition complementary electrochromic device, 1 and 4 are layers of transparent conductive glass, which can be rigid FTO glass, ITO glass, AZO glass, transparent conductive graphene glass, or FTO glass, ITO glass, or AZO glass modified with nanocrystals (Pt, Au, ITO, etc.) or conductive polymers (polyaniline, polythiophene, polypyrrole, etc.). Alternatively, it can be a flexible transparent conductive electrode (e.g., PET / ITO, PET / graphene electrode, PET / conductive polymer). 2 is the cathode electrochromic material, which can be WO3, MoO3, TiO2, Nb2O5, WMoO3, etc. x WTiO x 、NbWO x This is a complementary electrochromic material of I- nonmetal deposition. The cathode electrochromic material achieves color change through ion implantation. 3 is the electrolyte layer, which is a mixture of ZnCl2 salt-in-water and ZnI2. The electrolyte is prepared by adding ZnCl2 to 10 mL of heated deionized water until it is nearly saturated, then adding ZnI2 until it is saturated, and letting it stand for a period of time. During the electrochromic process, I- in the solution can generate solid iodine on 4. This is the complementary electrochromic material of 2. The electrolyte can be a ZnCl2 salt-in-water electrolyte or other zinc salt water system or organic electrolyte. The circuit is led out through 1 and 4 with wires respectively.

[0027] Example 2 - WO3-I2 Complementary Electrochromic Device

[0028] In the WO3-I2 complementary electrochromic device, the electrode materials of 1 and 4 are FTO glass, the cathode electrochromic material is WO3 prepared by magnetron sputtering on FTO, and the electrolyte is ZnCl2 salt in water with a small amount of ZnI2.

[0029] The principle of the WO3-I2 complementary electrochromic device: In the initial state, the device is transparent. When a voltage is applied through the wires connected to terminals 1 and 4, at a positive voltage of 1.5-1.8V, the cathode electrochromic material on terminal 2 gains electrons and simultaneously injects ions, changing it to a colored state. Simultaneously, I in the electrolyte on terminal 3... - Electron loss at position 4 produces solid iodine. The combined colors of the two materials deepen the color to black, making it almost opaque. When a negative voltage of approximately -1.5V is applied, the cathode electrochromic material at position 2 loses electrons and releases ions, becoming a decolorized state. Simultaneously, the solid iodine generated at position 4 gains electrons and transforms into I₂. - Redissolved in electrolyte 3, this device exhibits greater transmittance during fading compared to traditional complementary electrochromic devices that require the preparation of two electrochromic materials, thus providing a wider modulation range.

[0030] Depend on Figure 2It is known that the transmittance of the device in the range of 400-800nm ​​is about 55-75%. Compared with traditional complementary devices, the non-metallic deposition complementary electrochromic device of iodine only requires the preparation of one electrochromic material, namely the cathode electrochromic material. When fading, it increases the light transmittance, and when coloring, the color of iodine is more deeply superimposed, almost blocking all the light, thus realizing color-neutral electrochromic tone control.

[0031] Figure 3 This demonstrates that the WO3-I2 complementary electrochromic device has excellent cycle stability.

[0032] Comparative Example 1 - WO3-PANI Complementary Electrochromic Device

[0033] This comparative example uses a complementary electrochromic device with the same structure as Example 2, the difference being that the electrolyte is 1M LiClO4 / PC, and polyaniline PANI is used as the color-changing layer to prepare a WO3-PANI complementary electrochromic device. Figure 4 The WO3-PANI complementary electrochromic device was assembled in the following manner: 1 and 5 are FTO glass, 2 is WO3, 3 is 1M LiClO4 / PC, and 4 is PANI. WO3 was sputtered using magnetron sputtering, and PANI was deposited by electrodeposition, i.e., 0.25M aniline AN was dissolved in 0.5M H2SO4 and deposited for 600s using transverse current electrodeposition at a current of 1mA.

[0034] Depend on Figure 5 It can be seen that the WO3-PANI complementary electrochromic device still allows a lot of visible light to pass through when it is colored, but only about 60% transmittance when it fades. Its modulation rate is significantly lower than that of the WO3-I2 complementary electrochromic device.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition, characterized in that, The complementary electrochromic device includes two conductive layers, with an electrochromic layer and an electrolyte layer within the two conductive layers. The electrochromic layer is a cathode electrochromic material, and the electrolyte layer contains iodine ions. A voltage is applied through a wire connected to the conductive layer. When a positive voltage is applied, the device is in a colored state, and when a negative voltage is applied, it is in a decolored state. The electrolyte layer is a blend of zinc iodide and zinc salt electrolyte solution, wherein the zinc salt electrolyte solution includes an organic solution of zinc salt or an aqueous solution of zinc salt. The cathode electrochromic material is tungsten trioxide.

2. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 1, characterized in that, It is in the colored state when a positive voltage of 1.0~2.0 V is applied.

3. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 1, characterized in that, It is in a decolorized state when a negative voltage of -2.0 to -1.0 V is applied.

4. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 1, characterized in that, The conductive layer is a transparent conductive layer, including a rigid conductive electrode and a flexible conductive electrode. The rigid conductive electrode includes at least one of FTO glass, ITO glass, AZO glass or conductive graphene glass, and the flexible conductive electrode includes at least one of PET / ITO, PET / graphene electrode or PET / conductive polymer.

5. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 4, characterized in that, The rigid conductive electrode further includes FTO glass, ITO glass, and AZO glass modified with conductive polymers or nanoparticles. The conductive polymers include at least one of polyaniline, polythiophene, or polypyrrole, and the nanoparticles include at least one of Pt nanoparticles, Au nanoparticles, and ITO nanoparticles.

6. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 1, characterized in that, The cathode electrochromic material is coated onto a conductive layer by magnetron sputtering, electrochemical deposition, hydrothermal method, or spin coating.

7. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 1, characterized in that, Organic solutions of zinc salts are electrolyte solutions containing zinc salts in water.

8. The color-neutral WO3-I2 complementary electrochromic device based on reversible iodine electrodeposition according to claim 7, characterized in that, The zinc salt electrolyte solution is a zinc chloride electrolyte solution in water. The preparation method of the blend of zinc iodide and zinc salt electrolyte solution includes: adding zinc chloride to heated water, adding zinc iodide when the solution is close to saturation until the mixed solution is saturated, and obtaining the blend of zinc iodide and zinc salt electrolyte solution.

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